In related art, image pickup apparatuses picking up an image of a structure in a living body part are used in biometrics authentication systems or the like, and, for example, various fingerprint authentication systems performing authentication of a living body through the use of fingerprints of fingers have been proposed (refer to Patent Documents 1 to 3). In such a fingerprint authentication system, the thickness of an image pickup apparatus is large, so arranging the image pickup apparatus outside the authentication system as described in Patent Document 1, and independently arranging an optical system (an image pickup lens) and a detection system (an image pickup device) as described in Patent Document 2 have been mainstream.
However, in recent years, a reduction in profiles of authentication systems is in increasing demand, thereby it is desired for image pickup apparatuses mounted in the authentication systems to have a smaller profile. Therefore, in Patent Document 3, an image pickup apparatus using a light guide plate has been disclosed. More specifically, a light source is brought into contact with an end section of the light guide plate, and light is repeatedly reflected in the light guide plate, thereby the light guide plate is allowed to function as a surface-emitting light source, and a living body (a finger) is placed on the light guide plate to pick up an image. The arrangement of a light source which generally has a wide angle distribution is fixed by such a configuration, so a reduction in the profile of the image pickup apparatus is achieved.
On the other hand, in such an authentication system, a high security level is in demand. In authentication using a fingerprint, a fingerprint pattern as an object subjected to authentication is easily forged, so there is the risk of a reduction in the security level of authentication. Therefore, in Patent Document 4, a vein authentication system performing authentication of a living body through the use of veins of a finger has been proposed. In this case, veins are structures inside the finger, so it is difficult to forge an authentication pattern, and compared to fingerprint authentication, authentication with a higher security level may be performed.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-312748    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2006-181296    Patent Document 3: Japanese Unexamined Patent Application Publication No. 2006-285487    Patent Document 4: Japanese Unexamined Patent Application Publication No. 2006-146612